title: Echocardiographic assessment of β-adrenoceptor stimulation-induced heart failure with reduced heart rate in mice.
abstract: 1. Chronic injection with the β-adrenoceptor (β-AR) agonist isoproterenol (ISO) has been commonly used as an animal model of β-AR-induced cardiac remodelling and heart failure. This ISO-treated model usually exhibits significantly decreased conscious heart rate (HR). However, the HR in treatment groups is usually adjusted to the same levels by anaesthesia to assess cardiac geometry and function. In the present study, we report a method of echocardiographic assessment that represents the true cardiac geometry and function under conditions of ISO withdrawal. 2. Briefly, C57BL/6 mice were treated with 5 mg/kg per day ISO for 12 weeks. Cardiac geometry and function were assessed by high-resolution echocardiography in vehicle (saline) - and ISO-treated mice that were either conscious or anaesthetized using different concentrations of isoflurane. 3. The cardiac β-AR response was decreased in ISO-treated mice, as evidenced by markedly decreased conscious HR. Vehicle- and ISO-treated mice did not differ in terms of cardiac geometry or function when HR was adjusted to the same level (400 b.p.m.) in both treatment groups, but cardiac geometry and function did differ when a low (1%) rather than high (1.5% or 2%) isoflurane concentration was used to adjust HR. Furthermore, 3 day ISO withdrawal eliminated the difference in conscious HR between the two groups. In addition, the groups differed in cardiac geometry and function regardless of the isoflurane concentration used. 4. In conclusion, using isoflurane to decrease the HR of treated groups to the same level may mask left ventricular dysfunction in ISO-treated mice. Withdrawal of ISO eliminated the difference in basal HR between the ISO-treated and control groups on echocardiography, allowing a more accurate assessment of cardiac pathological and functional changes.
authors.affiliation: Institute of Vascular Medicine, Peking University Third Hospital, Beijing, China; Key Laboratory of Cardiovascular Molecular Biologyand Regulatory Peptide, Ministry of Health, Beijing, China; Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.forename: Zhi-Zhen
authors.initials: ZZ
authors.lastname: Lu
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.forename: Yao
authors.initials: Y
authors.lastname: Song
authors.forename: Han
authors.initials: H
authors.lastname: Xiao
authors.forename: You-Yi
authors.initials: YY
authors.lastname: Zhang
mesh_terms: D000318:Adrenergic beta-Agonists; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D000818:Animals; D004452:Echocardiography / Q000379:methods*; D006333:Heart Failure / Q000139:chemically induced* / Q000000981:diagnostic imaging* / Q000473:pathology; D006334:Heart Function Tests; D006339:Heart Rate / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects; D007530:Isoflurane; D007545:Isoproterenol; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000473:pathology; D020257:Ventricular Remodeling
chemical_list: D000318:Adrenergic beta-Agonists; D018685:Anesthetics, Inhalation; D007530:Isoflurane; D007545:Isoproterenol
keywords: adrenoceptor; echocardiography; heart failure; heart rate; isoflurane